Various devices for the feed and reversal of motion of the ribbon of typewriters and like machines are known, in which the ribbon is housed in a cartridge or like container, which is mounted on the typewriter or replaced with certain operations involving insertion of the whole cartridge in to a suitable housing.
In the known devices usually some toothed means are provided, hinged on the typewriter frame, and engaged in rotation with the ribbon spools during the insertion of the cartridge in the same typewriter.
The means drive forward the two spools, while the control of the reversal of the direction of motion is obtained by means of feelers which monitor continuously the amount of ribbon which is wound on a spool and, at the right moment, provide the reversal action.
Said devices present at least two groups of disadvantages, one resulting from the complexity of construction, which requires, for the movement, toothed wheels for each spool, dog clutches and related supports, pivots and the like, with high production costs and difficulty of maintenance. The other group of disadvantages is related to the very mounting of the cartridge, since it is necessary that the feelers sensing the amount of ribbon wound on a spool be inserted in the cartridge and extracted from it when the cartridge is mounted on, or extracted from the typewriter, so that it becomes necessary to provide a supplementary mechanism which allows to preset, automatically or by manual operation, such sensing means in the cartridge.